Apparatus and method for programming PMOS memory cells
AssigneeProgrammable Microelectronics Corporation
InventorsChing-Hsiang Hsu, Shang-De Ted Chang, Nader Radjy
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Abstract
A program voltage of a first level is applied to the control gate of a PMOS floating gate memory cell to realize an injection of hot electrons induced by band-to-band tunneling (BTBT) into the floating gate of the cell. As the threshold voltage of the cell increases due to the accumulation of charge on the floating gate, the injection of BTBT induced hot electrons subsides. The program voltage is reduced to a second level which induces the injection of channel hot electrons (CHE) into the floating gate, thereby boosting the rate of charge accumulation on the floating gate.
Claims17
A method of programming a PMOS floating gate memory cell having a p+ source, a p+ drain, a floating gate, and a control gate, said method comprising the steps of:
- injecting into said floating gate hot electrons induced predominantly by band-to-band tunneling until a predetermined event occurs;
- and
- after said predetermined event occurs, predominantly inducing injection of channel hot electrons into said floating gate.
A method of programming a floating gate memory cell by using a programming voltage to successively alternate between (1) predominantly injecting hot electrons induced by a band-to-band tunneling into said floating gate and (2) predominantly injecting channel hot electrons into said floating gate.
Dependencies are inferred from the claim text.